Light sensitive, silver halide based color photographic products typically comprise a number of constituents in each of their successive layers. The physical grain sizes, chemical structures and chemical compositions of the constituents, as well as the manufacturing process and apparatus used to supply the constituents and apply the layers, can have profound effects on the sensitometric properties or characteristics of the product upon exposure and subsequent development. Thus, variations in such parameters during manufacture of a product can lead, for example, to totally unacceptable products which must be scrapped at considerable expense to the manufacturer or to undesirable variations from run to run of a product which make use of the product difficult for the customer.
One known approach to controlling the sensitometric characteristics of a product has been to sample the product during manufacture; expose it in a controlled manner, and then develop or process it to permit such characteristics to be measured and any necessary manufacturing process or product constituent changes to be made. The red, green and blue density curves have been plotted and then compared to previously determined aim responses for the particular product. A high degree of skill has been required for the reader of such curves to make such comparisons at several points for each color, for such parameters as the speed response, the contrast, the density, the stain limit and the color balance; and then to decide how to adjust the product or the manufacturing process to produce product within acceptable limits. While such analysis has been done, the production process either has been stopped awaiting test results or has continued running on the assumption that the results would be acceptable. In the former instance, undesirable delays in production have resulted; while in the latter instance, substantial quantities of product have been scrapped when the result were not acceptable.
A similar approach to such a problem is disclosed by U.S. Pat. No. 3,990,898 which teaches an empirical method to adjust the color speed balance of a photographic film using filter dyes. Aim values are established for acceptable color speed balance of the product, using samples from previous production runs. Samples are then taken from current runs and sensitometric curves are prepared for the samples. If the current product deviates beyond a tolerance range for color speed balance, the level of at least one filter dye is changed. Further samples incorporating this change are then taken and their color speed balance measured to determine the effectiveness of the dye change. This process is then repeated until the desired effect is achieved.
Thus, in the art of manufacturing photographic films and papers, a need has existed for a method and an apparatus for determining and displaying how a photographic product's color density responses compare to established quality indicator parameters or standards and for predicting and displaying how changes in control variables for the product or its production process will bring the product within desired limits. Such a method and apparatus would enable the manufacturer to adapt relatively quickly to changes in the product during manufacture, which changes are caused by unexpected variations in the constituents of the product, conscious changes in the design of the product, variations in the production conditions and the like.